The invention relates to an automatic turret lathe with a live spindle supported in a headstock so as to be drivable in rotation and axially displaceable and with at least one turret head which is located laterally and in front of the live spindle on the headstock and is provide with tool receivers placed at an angular distance from each other.
An automatic turret lathe of the above-described type is known. In this machine, the turret head is placed parallel to the live spindle in the headstock and can be accordingly pivoted around its indexing axis for the plane setting of the tools (disclosure of German patent application No. 1,477,170).
This type of plane tool setting requires a precise adjustment of the tool cutting edges on a cutting circle passing through the axis of the live spindle. This requirement limits the tool selection possibilities. Furthermore, a nonlinear path measuring system is necessary for plane setting, so that the feed to be performed on the basis of a movement on the arc of a circle can be compensated relative to a linear displacement. Finally, the setting angle of the tools depends on the part diameter.
It is one of the objects of the invention to provide an automatic turret lathe in which the disadvantages of the above-described design are avoided and the conditions are provided to obtain universal application for longitudinal turning, chuck work, rod and shaft machining with the simplest machine construction.
To realize this object, the invention applies to an automatic turret lathe with the characteristics of the above-described machine design, characterized by the fact that the turret head is located on a turret carriage which is mounted on the headstock so as to be adjustable perpendicular to the axis of the live spindle, is placed with its indexing axis at an acute angle to the axis of the live spindle, and carries the tools for outside as well as inside machining of the parts.
By equipping the automatic turret lathe with a turret head which can be adjusted radially to the live spindle for plane setting of the tools in connection with the axially adjustable live spindle, a cross-carriage system with the tools being fixed in the direction of the live spindle axis is obtained in these machines, creating optimum conditions with regard to tool arrangement and control as well as operating technology. The oblique arrangement of the indexing axis of the turret head to the live spindle axis at the same time allows favorable accommodation of all necessary auxiliary equipment in the working space for turning in the longitudinal direction as well as between end-points and to obtain a generally advantageous arrangement of tools.
A turret lathe is known in the prior art in which the turret head is placed on a carriage which is adjustable radially to the live spindle for plane setting of the tools (brochure of The Warner & Swasey Co., 1-SC, 1974).
However, in this design the turret head is placed on the carriage so as to be axially parallel to the axially immobile live spindle and in addition to its indexing motion, also performs an axial feed motion. This leads to the disadvantage that the tools, referred to plane setting, must have a projection depending on the longitudinal stroke, so that their cutting edges must at least be positioned at a large distance from the plane feed path which has an unfavorable effect on precision.
Further, an automatic turret lathe is also known in the prior art in which the turret head is placed on a turret carriage with its indexing axis at an acute angle to the axis of the live spindle. However, in this design the tools for inside machining and those for outside machining are placed on different turret heads, i.e., the tools for outside machining are located on a crown turret head, while those for inside machining are mounted on a star turret head (brochure of Cincinnati-NC Turning Centers, p. 15, 1972).
The dual arrangement of the turret heads in this known design requires a technically costly overall concept, because, on the one hand, one turret carriage each with the appropriate turret head indexing system must be provided for both turret heads, and, on the other hand, the wellknown collision considerations must be taken into account.
As for the design of the invention, it is favorable to place the turret carriage in a plane guide of the headstock which is essentially placed symmetrically to the axis of the axially displaceable live spindle, resulting in the important advantage that longitudinal guidance of the live spindle and plane guidance of the carriage are in a common plane, so that errors due to carriage tilting are eliminated.
In a preferred practical version of the invention, the indexing axis of the turret head is inclined 60.degree. to the live spindle axis, so that particularly favorable space relationships result in the working space to accommodate a tailstock or other auxiliary equipment.
In view of the desired simplified machine construction, the headstock is designed in one part and at the same time forms the machine bed.
According to the characteristic of the invention, the turret head carries the tools both for outside and for inside machining. In a preferred version, the tool receivers on the turret head are provided for alternate placement of outside machining tools and inside machining tools, where at least the tool receivers for outside machining tools are located on the periphery of the turret head and the tool receivers for inside machining tools are placed perpendicular to the former. Apart from the fact that this arrangement of outside and inside machining tools on the turret head makes an additional turret head unnecessary, the alternate arrangement of inside and outside machining tools makes it possible to use rotary inside tools to advantage on the turret head. In a special further refinement of the invention, the tool receivers are formed by at least one receiving surface, of which those for outside machining tools, when in working position, are located in a plane perpendicular to and penetrated by the live spindle axis, while the receiving surfaces for the inside machining tools, in their working position, are located in a plane parallel to the live spindle axis. It is of advantage if the preferably plane tool receiving surfaces form the base of groove-like depressions of the turret head. The walls of these groove-like depressions receiving the tool holders for inside machining tools will advantageously have a concave curvature, so that the turret head for inside machining of parts can be driven directly in front of the part clamping site of the live spindle, where the parts can enter the depressions of the turret head.
In a further favorable refinement of the invention, the tool holders of the outside machining tools are adjustable and lockable on the respective receiving surfaces of the turret head perpendicular to the live spindle axis and the tool holders for the inside machining tools are adjustable and fixable on the respective receiving surfaces parallel to the live spindle. Such an adjustability offers the further important advantage that the cutting edges of the outside and inside machining tools can be adjusted to an approximately identical cutting circle, so that bridging of the position distances otherwise present on turret heads in their set working position by means of an additional carriage path becomes unnecessary. Thus, shorter paths of the turret carriage and therefore, shorter and smaller construction components and auxiliary equipment will be sufficient.
In a special version of the invention, the position of the tool receiving surfaces for the inside machining tools in the turret head in their working position is selected such that when the turret head is projected on a plane through the indexing axis and live spindle axis, the distance of these tool receiving surfaces from the end of the neighboring receiving surfaces for outside machining tools, oriented toward the front turret head face, is greater by a multiple than their distance from the end of the receiving surfaces for the outside machining tools, oriented toward the back face of the turret head. On the basis of the arrangement of the tool receiving surfaces for the outside machining tools perpendicular to the receiving surfaces for the inside machining tools, referred to their working position, the tool receiving surfaces for inside machining tools can have an optimum length with a compact turret head diameter with a relatively small axial dimension of the turret head, particularly also with consideration of its oblique placement at an angle of especially 60.degree. to the live spindle axis. This is optimum because the ratio of the length of the clamping area to the size of the tool holders and tools favors the desired approximately identical cutting-edge position of both types of tools. The possibility of adjusting the tools in such a way that their cutting edges essentially can be adjusted to a common working point offers the further advantage of a collision-free indexing of the tools, so that the working range can be further expanded by the fact that the outside machining tools, if desired, can be mounted on the receiving surfaces for the inside machining tools with a displacement of these receiving surfaces in longitudinal direction.
Furthermore, the automatic turret lathe is characterized by a preferably removable preturning device which can be used for plain turning and has a carriage which is guided in the headstock and carries a tool holder and which can be coupled mechanically preferably with the turret carriage for its drive. The carriage of this preturning device, when referred to the live spindle, is advantageously placed to be diametrically opposite the turret carriage and can be coupled with the latter via a lever drive in such a way that their feed displacements are in opposite direction and coincide with each other. Accordingly, only one transverse drive is needed for radial control of the turret carriage and the preturning device.
In order to allow an advantageous performance of plain turning in accordance with the objective of the present invention, a further refinement of the invention allows mounting of a guide system overlapping the spindle head of the live spindle and mounted coaxially to the live spindle on the headstock, by means of which plain turning parts can be maintained to be rotatable in the immediate zone before the point of attack of the tool cutting edges. Furthermore, to perform turning work, a tailstock is placed between the ends of the live spindle, for which purpose a tailstock sleeve is provided in the headstock parallel to the live spindle so as to be rotatably and axially displaceable and axially adjustable synchronously with the live spindle by the same path distances. For a synchronous axial adjustment of the live spindle and tailstock sleeve, a common adjustment device is of advantage by means of which a drive dog can be adjusted through which the live spindle as well as the tailstock sleeve can be simultaneously adjusted in the lengthwise direction. So that it will not be necessary to move the drive device for the live spindle together with the latter during feed movements and accordingly maintain the moving masses at a minimum, the drive dog forms a fixed transmission housing on the sleeve-like bearing housing of the live spindle in order to accommodate an auxiliary transmission, by means of which the live spindle can be driven in rotation by a stationary drive system. The drive system is advantageously provided with a driven shaft driving the auxiliary transmission and extending parallel to the sleeve-like bearing housing of the live spindle, this shaft passing through the drive dog and the latter being displaceably guided on it. So that the lathe center of the tailstock can be brought from its operating position into the standby position, if no turning between ends is to be done, the tailstock sleeve is designed so that it can be twisted and the tailstock can be pivoted back and forth between the two mentioned positions. At the same time, provision is made for the adjustment device providing the longitudinal displacement of the live spindle and tailstock sleeve will be used simultaneously for the rotational drive to turn the tailstock sleeve.
The axial adjustment of the live spindle can be realized technically with particular advantage if it is supported so that it can be driven in rotation in a bearing housing formed as a sleeve and placed into the headstock so as to be axially displaceable.
The invention furthermore deals with an automatic feed of a material bar inserted into the live spindle of a turret lathe, particularly an automatic turret lathe, for which the axial motion of the working spindle is utilized according to the invention. In order to realize such an automatic material feed, a guide piece of a bar feed-guide device holding the material bar is provided, extending into the live spindle from its back end and a supporting member which can be mounted to the back end of the material bar is guided on this guide device in such a way that it can be adjusted relative to the guide piece only with an axial motion of the live spindle taking place in the feed direction. This assures that the material bar, when it is transported by the live spindle in the direction of the machine working space remains in the feed position when the live spindle is retracted again after release of the material clamping device by finding support at the guide piece via the support member, while the feed path of the live spindle is suitably adjusted to the desired part length. It is of advantage here to provide the end of the guide piece located in the interior of the live spindle, preferably immediately in front of its material clamping device, with a stop on which the supporting member can be arrested in order to activate a shut-off device to shut down the machine when the material bar has been consumed. A particularly favorable design results in this connection if the guide piece has a tubular form and the supporting member is formed by a sliding piece which adjoins the latter at the inside circumference with friction and is attachable and clampable to the back end of the material bars to be machined. The preferably tubular guide piece can be fixed relative to the live spindle, so that the guid piece forming the supporting member will shift relative to the guide tube even during the feed motion of the live spindle. However, it is of advantage to refine the design in such a way that a relative motion between guide tube and slide piece takes place only for the purpose of the material bar feed and the two parts will move together with the live spindle during the working feed through the latter, so that wear of the slide piece will be limited to a minimum.